Vernal Pools

Photo by Phil Robertson

Vernal pools are special seasonally-flooded wetlands that occur in shallow depressions, usually in a grassland landscape. The depressions are underlain by a layer that slows the percolation of water so that the pools are inundated for much of the winter and spring. Vernal pools may be isolated from each other, but they are often part of a cascading pool and swale complex. Because vernal pool habitats alternate between inundation and desiccation, they support a unique flora and fauna compared to adjacent habitats. Many species inhabiting are considered threatened or endangered by state and federal resource agencies and they grow nowhere else in the world. The various flower species begin to flower as the pools dry in the spring, and usually results in concentric rings of different colors.